Image processing apparatuses capable of applying various image processes such as color tone correction or rotation to image data taken by an electronic camera, for example, are well known in the art. Such image processing apparatuses display thumbnail images which are reduced images on the screen thereof so as to allow a user to confirm a plurality of input image data at sight. One such image processing apparatus disclosed in Japanese Patent Application Publication No. 2000-215322 applies predetermined image process to a thumbnail image that has been selected as image data to be processed by a user and displays a result of the image process on the screen thereof.